The invention relates to a system comprising a vehicle having an automatic radio-based vehicle safety unit and having an access control device, and comprising an access element assigned to the vehicle safety unit, the vehicle safety unit having several low-frequency transmitting antennas, and the access element having a low-frequency receiver, and by means of the access control device, the spatial position of the access element relative to the vehicle being detectable by means of the principle of electromagnetic distance and angle measuring between the transmitting antennas and the receiver.
According to the state of the art, such as European Patent Document EP 0 984 123 A2, automatic radio-based vehicle safety units are utilized for the control or authentication of an access element. The access element is usually a radio key, by which a user of a certain vehicle can procure access to this vehicle without actively using the key assigned to this vehicle. These vehicle safety units are therefore also called radio-based locking systems.
Furthermore, in the case of modern radio-based locking systems, the vehicle cannot be locked when the radio key is situated in the vehicle interior by being spatially located by way of the locking system.
Vehicles having an electrified drive train usually have a charging interface to an external charging source. The transmission of electric power in order to, for example, charge an electro-chemical energy accumulator of the vehicle, usually takes place in a wired or inductive manner.
In the case of wired charging methods, the vehicle has to be connected by way of a charging cable with the external charging source, such as a charging station, in order to carry out a charging operation. In the case of inductive charging methods, the power transfer takes place by way of an electromagnetic exciter field of a vehicle-external primary coil to a vehicle-side secondary coil by way of electromagnetic induction at the secondary coil. The transmission efficiency of the electric power in this case is a function of the relative spatial position of the secondary coil with respect to the primary coil. In a preferred position area of the secondary coil relative to the primary coil, the fraction of the exciter power, which occurs as a power loss during the charging, is approximately minimal.
The object of the prior art is bringing the secondary coil into the charging position. International Patent Document WO 2011/006884 A2, for example, describes an electronic positioning aid for a vehicle having a primary coil, which positioning aid utilizes the reflection characteristics of a housing of the primary coil situated on the ground.
It is an object of the invention to describe an improved system, comprising a vehicle having an automatic radio-based vehicle safety unit and having an access control device, and comprising an access element assigned to the vehicle, the vehicle having several low-frequency transmitting antennas, and the access element having a low-frequency receiver, and by means of the access control device, the spatial position of the access element relative to the vehicle being detectable by means of the principle of electromagnetic distance and angle measuring between the transmitting antennas and the receiver.
Advantageous embodiments and further developments of the invention are contained in the dependent claims.
According to the invention, the system comprises a vehicle-external induction charging unit having a primary coil, in which case, the vehicle has a secondary coil for the inductive charging of the vehicle at the induction charging unit, and the induction charging unit has at least one low-frequency receiving antenna, and the access control device can carry out a detection of the location position of the induction charging unit relative to the vehicle by means of the principle of electromagnetic distance and angle measuring between at least two transmitting antennas of several low-frequency transmitting antennas and the at least one receiving antenna.
This means that two low-frequency transmitting antennas of the vehicle, which are operated by the access control device, in addition to the localization of the access element, can also be used for distance and angle measuring with the at least one receiving antenna of the induction charging unit. In this manner, the vehicle-external induction charging unit can be spatially located by way of components of the locking system of the vehicle and the access control device. This permits a location position determination of the induction charging unit relative to the vehicle.
According to a preferred embodiment of the invention, the secondary coil for the inductive charging takes up a charging position which is situated in a preferred spatial position area with respect to the primary coil. For establishing the charging position, the system further detects, by means of the location position and the charging position, at least a partial travel trajectory, along which the charging position can be taken up by the secondary coil.
In the preferred position area, the fraction of the exciter power, which occurs as a power loss during the charging, is approximately minimal.
Furthermore, it is useful for the access control device to drive the at least two transmitting antennas, for the access control device to comprise a first high-frequency communication unit, for the induction charging unit to have an induction control device, for the induction control device to comprise a second high-frequency communication unit, for the induction control device to be assigned to the at least one receiving antenna as measuring unit of the electromagnetic distance and angle measuring and to measure the induction signals of the at least one receiving antenna, for the induction signals to be transmissible from the induction control device to the access control device, and for the access control device as the arithmetic unit to detect the location position by triangulation by means of the induction signals.
The access control device therefore operates at least two transmitting antennas of the radio-based locking system in order to carry out angle and distance measuring between the transmitting antennas and with the at least one receiving antenna. According to preferred further developments, the charging unit has precisely one receiving antenna or precisely two receiving antennas. The measured induction signal can be sent by the induction control devices to the access control device. The measured induction signal is used as an input variable for the access control device in order to calculate the location position by triangulation.
According to a further embodiment of the invention, the access control device or a further control device of the vehicle detects the travel trajectory by means of the location position, the vehicle automatically carrying out a driving maneuver corresponding to the travel trajectory, or the vehicle informing a driver of the vehicle by way of a suitable human-machine interface of a driving maneuver corresponding to the travel trajectory.
The notification of the driver can take place, for example, by a fading of a steering recommendation into a head-up display of the vehicle or by a language statement, which can be compared with a language statement of a navigation system of the vehicle.
For implementing a driving maneuver, the driver is therefore assisted by way of a human-machine interface by emitted instructions (for example, “steer left), or the trajectory is used as an input variable for a driver assistance system which moves the vehicle automatically into the charging position.
According to a further embodiment of the invention, the first high-frequency communication unit first sends out a coded search signal. After the reception of the search signal by the induction control device, the second high-frequency communication unit sends a coded confirmation signal to the access control device. The reception of the confirmation signal triggers an initialization routine between the at least one transmitting antenna and the at least one receiving antenna, which is carried out by the access control device and by the induction control device. After the initialization routine, the at least two transmitting antennas will emit a coded electromagnetic positioning signal, the magnetic fraction of the positioning signal having a specified field orientation or a specified field intensity with respect to the vehicle coordinate system. The at least one receiving antenna receives the at least two positioning signals of the at least two transmitting antennas, and the induction control unit measures a magnetic field vector for each positioning signal, which magnetic field vector is clearly assigned to one of the at least two transmitting antennas by means of the coding of the position signal. The magnetic field vector is transmitted as a measured induction signal from the induction control device to the access control device. According to a triangulation method, the access control device computes the local position of the transmitting antennas with respect to the receiving antennas, which clearly describes the location position. Furthermore, the access control device or a further control device of the vehicle detects at least a partial travel trajectory, along which the location position can be approximated to the charging position.
When a driving maneuver takes place after the detection of the travel trajectory, the determination of the location position will be repeated in real time, in order to update the travel trajectory. When the charging position has been reached, the updated travel trajectory describes a stopping maneuver. The vehicle comes to a stop during a stopping maneuver
The invention is based on the considerations described in the following:
In a plurality of applications, it is the goal to determine the distance of an object (for example, a vehicle) with respect to another object (for example, a vehicle key). Radio technology in the high-frequency and low-frequency band here offers possibilities to do so in a wireless manner by means of measuring field intensities and run times of electromagnetic alternating fields. One example are modern radio-based locking systems of vehicles, such as a keyless access, in the case of which the vehicle acts as a transmitter and the vehicle key acts as a receiver.
Modern locking systems of vehicles provide the user with a comfortable access to the vehicle. These are automatic systems by means of which a vehicle can be unlocked without any active use of a car key. The presence of the car key within a specified relative local area around the vehicle is sufficient for the unlocking. As soon as the key approaches the vehicle up to a locally sensitive area, a coded query signal with a frequency in the low-frequency range is emitted by way of several antennas distributed in the vehicle. The locking system will then go into a receiving mode in the ultrahigh-frequency range in order to possibly receive a confirmation signal of the vehicle key. If the vehicle key, equipped with an RFID transponder, with a 3d coil or with a combination of three coils, is within the range of transmission, the query signal will be received and decoded by the key. The key will then send out the confirmation signal with a new coding in the ultrahigh-frequency range. If the confirmation signal “fits”, the vehicle will be unlocked.
In an inverse application case, the vehicle cannot be locked if the vehicle key is within a specified local area which may, for example, be the occupant compartment or the trunk, in order to prevent an accidental locking-in of the vehicle key.
It is suggested to use the locking system of the vehicle for determining the location position of a vehicle-external inductive charging unit for a vehicle with an electrified drive train. For this purpose, at least two clearly identifiable electromagnetic transmitter signals of antennas of the locking system are used in order to receive, at a receiver of the vehicle-external charging unit, signals from at least two different transmitter positions for angle and distance measuring. By triangulation, a clear conclusion can then be drawn concerning the position of the receiver with respect to the transmitter. By way of the same radio system, in addition, on the same frequency or on a different frequency, preferably in the high-frequency band, communication signals (for example, for the position description) can be exchanged between the at least 2 transmitters and the receiver.
The transmitters are integrated in the or at the vehicle, and the receiver is accommodated at the primary coil. By means of triangulation, a clear conclusion can be drawn concerning the position of the transmitter with respect to the receiver. By way of the same radio system, in addition, communication signals (for example, position data) on the same frequency or another frequency can be exchanged between the two transmitters and the receiver.
This permits a clear position determination with respect to transmitter and receiver of a high precision by several input signals and triangulation.
Depending on the vehicle type, the radio-based locking system has a defined number of transmitting coils by which an electromagnetic low-frequency field is generated, which is measured by a preferably three-dimensional coil or a combination of three individual coils, which covers three orthogonal spatial directions, in the vehicle access key. As a result, the distance of the key from the transmitting coil can be determined. By way of several transmitting coils in the vehicle, the actual spatial position of the radio key with respect to the vehicle can be determined. This indicates whether the key is situated outside or inside the vehicle. This information is useful for several applications in the vehicle, such as locking and opening the vehicle, or for the switch-on prevention in the case of an automatic engine start-stop function. This information can also be skillfully used for inductive charging systems of chargeable vehicles.
For the inductive charging, an optimal positioning of the vehicle-side coil, the secondary coil, in the spatial reference to the infrastructure-side coil, the primary coil, is necessary for a maximal power transmission efficiency during wireless charging. The radio-based locking system is used as a positioning system for the vehicle by the triangulation method. For this purpose, preferably at least two transmitting coils of the radio-based locking system are used on the vehicle side. An inductive charging station outside the vehicle has at least one receiver, which preferably has a three-dimensional design but, as an alternative, may have a one-dimensional design. Preferably, the receiver of the inductive charging station or the receivers of the inductive charging station correspond to the receiver in the radio key.
This has the special advantage that components of already existing radio-based locking systems can be used for the positioning (transmitter coils and their triggering for the position determination). The already installed transmitting coils of the locking system are utilized and are addressed by way of the existing access control device by way of the data bus. The transmitting antennas send a low-frequency signal with the desired parameters.
The utilization of the transmitting coils of the radio-based locking system results in a functional installation-space-neutral and weight-neutral expansion of the vehicle, without integrating further hardware in the vehicle for implementing this function.
By means of the attached drawings, a preferred embodiment of the invention will be described in the following. These drawings indicated further details, preferred embodiments and developments of the invention.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.